1. Field of the Invention
The present invention relates to an electron microscope apparatus which is preferably used for detecting a defect in a wafer, and, more particularly, to a scanning electron microscope for image picking-up of unevennesses on the surface of a sample.
2. Description of the Related Art
During processes for manufacturing a semiconductor device, there is executed in-line wafer inspection by which a defect in a wafer is inspected. The defect in the wafer is detected, and a reason for generation of the defect is located by analysis to realize yield improvement and stable operation of production lines.
Conventionally, an optical apparatus for inspecting a defect had been used for inspecting a defect in a wafer, but, recently, there has been used an apparatus for inspecting a defect by use of a scanning electron microscope. The scanning electron microscope may obtain an image of fine unevennesses on the surface of a sample.
Japanese Patent Application Laid-Open No. 2001-110351, and Japanese Patent Application Laid-Open No. 2002-83563 have disclosed a method in which an image of unevennesses on the surface of a sample is obtained by use of a scanning electron microscope.
Recently, a finer production process for manufacturing a semiconductor has also caused a finer defect size. Accordingly, it is required to obtain an image of unevennesses for an image of the surface of a sample in a high-resolution manner and a high contrast one.